President Barack Obama Thursday declined to fire anyone for the lapses that allowed a suspected terrorist carrying explosives to board a plane for Detroit on Christmas Day, and said for the first time that he bears the ultimate responsibility for any breach that endangers Americans.

"I am less interested in passing out blame than I am in learning from and correcting these mistakes to make us safer, for ultimately the buck stops with me," Obama said. "As president, I have a solemn responsibility to protect our nation and our people, and when the system fails, it is my responsibility."